1. Field of the Invention
This invention relates to the field of aromatic compound synthesis and, more particularly, to the preparation of alkyl aromatic compounds and catalyst compositions useful therefor.
2. Description of the Prior Art
Alkylation of aromatic hydrocarbons utilizing crystalline aluminosilicate catalysts has heretofore been described. U.S. Pat. No. 3,251,897 to Wise describes alkylation of aromatic hydrocarbons in the presence of X- or Y-type crystalline aluminosilicate zeolites, specifically such type zeolites wherein the cation is rare earth and/or hydrogen. U.S. Pat. No. 3,751,504 to Keown, et al. and U.S. Pat. No. 3,751,506 to Barress describe vapor phase alkylation of aromatic hydrocarbons with olefins, e.g., benzene with ethylene, in the presence of a ZSM-5 type zeolite catalyst.
Processes for the catalytic methylation of aromatic hydrocarbons, e.g., toluene to provide a mixture of xylene isomers, employing hydrogen and carbon monoxide as the methylating agent are described in U.S. Pat. Nos. 3,718,704 to Chapman, et al. and 4,086,289 to Seitzer. Due to the nature of the catalysts, in the case of Chapman, a mixture of certain metal oxides such as zinc oxide and chromia (zinc chromite) and in the case of Seitzer, zinc chromite mixed with an alkali metal exchanged molecular sieve containing an excess of alkali metal carbonate, these processes are incapable of incorporating alkyl groups other than methyl into the aromatic ring.